Circuit failure protection device



* Nov. 1953 .I. v. v. ELSWORTH ,660,48 l CIRCUIT FAILURE PROTECTIONDEVICE 7? Filed March 28, 1952 1 APP.

3nventor (Ittornegs Patented Nov. 24, 1953 CIRCUIT FAILURE PROTECTIONDEVICE John Van Varick Elsworth, Watertown, N. Y., as-

signor to The New York Air Brake Company, a corporation of New JerseyApplication March 28, 1952, Serial No. 279,107

This invention relates to air brakes and particularly to safety systemsfor electro-pneumatic brakes. Specifically the invention is concernedwith a circuit failure protection device of the type described andclaimed in applicants earlier patent, No. 2,527,920 which issued onOctober 31, 1950. As a basis for disclosing the principle of theinvention, it will be described as applied to the 24-RL brake equipmentwhich is a commercial standard familiar to persons skilled in the art.

Basically this equipment is a dual brake system in which a completeautomatic brake system and a. complete electro-pneumatic straight airsystem exist side by side throughout the train. They operate the samebrake cylinders through the same relays. They are controlled by the sameengineers brake valve, which may be set to operate the straight airsystem or the automatic system by shifting a two-position selector.

A few characteristics are of present importance, and will be mentioned.The automatic brake pipe retains all its usual characteristics. Hence, abreak-in-two will inevitably cause an emergency application. Moreover,no matter how the selector is set, the engineers brake valve always hasone and the same emergency position, which will produce an automaticemergency position, which will produce an automatic emergencyapplication. Hence, the major safety factors characteristic of automaticoperation are always available, and are in no way dependent on anyelectrical function or straight-air function. The system loses nothingby the presence of the electro-pneumatic straight-air system.

The straight-air pipe is divided into car length units by chokes, thoughit is connected continuously throughout the train. The pressure in eachunit is controlled by an electrically actuated inlet valve and anelectrically actuated discharge valve. All such units are controlled bya master controller located at the head of the train. Since it isimpracticable to operate the electrical part of the system on a closedcircuit basis, the electrical part of the system cannot have a fail safecharacteristic, and since the car-lengths of the straight air pipe aresemi-isolated, units comprising more than one car, cannot be properlycontrolled by adjacent cars, in the event of failure of someelectrically operated valve.

Trains equipped with the 24-RL brake are operated on the straight-airprinciple under normal conditions. The engineer's brake valve is set toestablish a desired pressure in the control pipe. This pressure puts themaster controller 2 Claims. (Cl. 303-26) plication of the brakes.

into action, and the latter through electrically actuated applicationand releasevalves establishes a related pressure in the straight-airpipe. The pressure so established exercises a follow-up or neutralizingeffect on the master controller, so that establishment of the desiredstraight-air pipe pressure puts the master controller in balance,whereupon its action ceases.

The circuit failure protection device described in applicants earlierpatent mentioned above avails of the fact that if there is leakage fromthe straight air pipe during a brake application, a cyclic functioningof the master controller will result. If this cycling becomes too rapidas would be indicative of a dangerous condition, an electricallycontrolled safety device operates to produce an automatic brakeapplication.

According to applicants earlier patent, a magnet valve is actuated eachtime the master controller moves to energize an application magnet, thuscyclic operation of the master controller causes cyclic operation of themagnet valve. The magnet valve controls the flow of air from a pressuresource such as the locomotive main reservoir to a volume which isconstantly vented at a restricted rate. As long as the period betweenthe cycles is sufficient for the pressure in the volume to bedissipated, the safety control device does not operate to produce anautomatic ap- According to the present invention, the pressure fluid issupplied to the control volume under a pressure head which variesinversely relatively to the force with which the brakes are applied.Thus when a heavy application is in effect the control volume is chargedat a slower rate than when a light application is in eifect. In thisway, with a heavy application of the brakes the frequency with which themaster controller cycles must be higher to cause the safety device tofunction than would be necessary if a light application were in effect.Thus the response of the safety device is not affected by pressure headin the straight-air pipe.

By use of the present invention it is possible to make a closerselection between a system which is in safe operating condition and onewhich is in unsafe operating condition than was possible by use of theapparatus described and claimed in applicants patent mentioned above.

While the invention is illustrated and will be,

described as it is embodied in the 24-RL brake equipment, it will beapparent to those skilled in the art that the invention can be used inthe same or similar form with other brake systems.

The invention will be described having reference to the accompanyingdrawing which is a diagram of that portion of the 24-RL equipment whichis affected by the invention. Certain parts of this brake equipment havebeen omitted from the drawing for the sake of clarity.

Aportion of the engineers brake valve appears in elevatipn at til, Theengineers brake valve is convertitile for operation selectively on thestraight-air principle and the automatic principle, and when set foroperation on the auto; matic principle operates the brakes by c ontrgllthe pressure in the normally charged brake pipe l2. When set to operateon the electroggeu matic straight-air principle, the engineerfs brakevalve I controls the pressure in the straight-ail? pipe I3. It does soindirectly by controlling the pressure in a control pipe I'd'sometimespalled" the number eleven pipe because that'happens to be theidentifying nugnber cast on the pipe easiest 9? the eee eerfs Pee sValveetes li e p n P wi bls he o e on crane -ts? eeet q' ls t' iv' 1illente sai jel i i eases a id ee s 'ie etea vle me a i111} io t lhv s.l5 and, sl-v e s i a fir 's i h eu fi the a fiai i I @9 1: onfthey mayoperate in any 'kn n in the art and since their f i ili i .1 d il .5 h 1?%F .1'-. 'agnt 'valves' cohtroll e dl'by the co n; troller l5, hroilghathfe" re circuitjwhichexas through it the tra I andcomprises the B 'd ea d y h et erB t e l aiivn. natedbvth le end App." and there}.

designated by'the' legend. Rel.

' lledsiwtbt Mem er 2,. at h e ii fdi'a "ag m 22,- Th i aiehtzair to mbe1"2 3 "at th'e right offa i "b f i ii p a m .4.; The. e diaphragmsareconnected together; e vtibn actu te? S it h s ere when. It pressure. inpipe I M'is t lfm e q h ght gainst i sin rin 2 2 i ev l ii in he tr iht-ai cl be the case), p'r'e'ssurein hambei jiifbalances that 2i," andthe" ring zgmiov s h, i new th ianhreemsm th fie m -9 m v. s t

r pressure has been established in the ir. s ei "Pipe me e Q em u the.pipev [sand consequentlyinchamber 21 w ll se a' further reverse movementof the dia- I -V Rod 25; carries acollar 21 which actuates the mean itv'm, 8 nd the r ea esv iqn afiiifibsimultaneously both in circuit closingd rections. The coa cting contacts are so contrived t s se magnet valveHand thereafter energize a dopen the appli cat'ion magnet valve l6.That, of icoiixise, is what produces the. rise of pressure in thestraight-air pipe 1.3. Under lap conditithe thef rlease Ina fiet valveremains energized bu he appnaiion; magnet valve is d e -energized itisfappare nt fronifwhat has just been said t a i fi e' er ttemptstomakean ap li-i 4 pipe or a serious leak therefrom, or if release magnetvalves fail to function or application magnet valves fail to function,there will be a disturbance of the operation of the master controller 5i5. Malfunctions short of complete circuit failure (against which othersafeguards are interposed) cause the master controller to cycle that is,cause it to reciprocate or; operate recurrently. The invention makes useof this recur- 10 rent operation or cycling to operate the serviceapplication valve in the engineers brake valve in and therebypro glucean automatic service application. Qpgratign gt, the service applicationvalve is 15,, efiectuated. byventing a pipe 3| known in the industryv asthe number ten pipe. So far as here naterial, the venting of the pipe 3|produces an automatic "service application. The term fautamatic is hereused in the technical sense to mean a brake application produced by theei eeti ties, l e.. .tem.-

ewviae i e s QQE KBQWQ et een t 15 @2 9; he 12 et ne 9 t e e me the maer qee i er; 1 uiw i s e h in 'iki s ener i es-n The a matur i he" windng we sta es. piib ei beet re e al e hite's bi a qq lv ress s r n He-teas emanates? x e w rom ad nlet east Thewhei? whine pres ure inhechambv r as were a; eqm in e flexi l ie @r'aemt as valve 4|. my V Wlhf2 lQ is first dete te n. the, ntrql pipe 14; ma t tis 5 sl pe ie l byhar n tr. spasm It Q Q QS f er rese -Quin anassace q esl or ri'thet' trig t: m r ev'el n'n m v T l- I at 1 este mcr b abvve b t he ea in t vaeis, sp;

t a. ai i i re n ve di closed this t evtioe 4. s u d i ress r fluiqiiiq' ai res rv i nd r Q'Q 'ei lqtta ve t, P les valve tairicl cl s. wan tamer man betw q y. 1), tion 'anriithe can realfie ib difie fi n Hil =b k1- APlQ l-Y mm afsli ebl in he nide k. st edjrem te't vqmi d aphr m sere a valves- Stem .8 .h j ead Por on,

d acent, tQ diaphra m 51 the efi t'i jfirst to en r ize an l s he m-mmsybiaetf l emri ssi tins-S Th swhenthe ,w siine tiled/sa ine ed. (ha

phragm valve 4| closes but each time that winding 34 is energized thevalve 4| is open. Valve 4| .remains open so long as the winding 34 isenergized. Pressure fluid is supplied from the pilot connection 43 andthe choke 44 past the valve. 4| to a small reservoir or accumulatorvolume 68.

The reservoir 68 is constantly vented to atmosphere through a choke 63.The size of the chokes 44 and 63 are so coordinated that the choke-69will substantially dissipate pressure in the volume, 68 under normaloperating conditions. The charging rate of flow to the volume 68 dependsupon the pressure in connection 43 and upon the frequency with which thewinding 34 is energized.

The pressure developed in the volume 68 reacts on the motor diaphragm Hof a normally closed switch which is indicated by the reference numeral12. The source of current for the lines APP., B and REL. is typified bythe battery 13 and the switch 12 is arranged to control the circuit fromthis battery through the winding 14 of the magnet valve generallyindicated at I5.

The valve 15 is biased to open by coil compression spring 16 and whenopen vents the pipe 3|. It follows that the winding 14 is constantlyenergized and holds the valve 15 closed and that maintained closure isdependent upon integrity of the circuit.

The switch 12 is normally closed but will be open if the reservoir 68 ischarged to a pressure above a certain predetermined maximum.

Operation of the device will be described assuming the electro-pneumaticsystem is being used.

A brake application is initiated by manipulation of the brake valve I!)to charge the control pipe I4. Charging of the control pipe |4 causesthe diaphragm 22 of the master controller I5 to flex to the right, asseen in the drawings thus successively closing the release andapplication switches. Closure of these switches energizes theapplication and release magnets which in turn cause the straight-airpipe I 3 to be charged. Initial charging of the control pipe [4 opensthe switch 45 thereby inhibiting energization of the winding 34. Switch45 closes when the volume 5| and the space 48 have been charged to apressure above a selected minimum value. The size of the choke 52 isselected, so that under normal conditions the straight-air pipe pressurehas suflicient time to develop and return the master controller l5 tolap position in which the application magnet is de-energized.

If straight-air pipe pressure fails to develop within this time period,the closure of switch 45 results in energization of the winding 34. Thisshifts the valve 35 to a position in which it interrupts the supply ofpressure fluid to the space 33 and vents that space. The pressure fluidin the space 66 will move the valve diaphragm 4| from its seat 42 andflow to the volume 68. The rate of fiow of the pressure fluid throughthe choke 44 to volume 68 varies in accordance with the pressure headexisting in the connection 43.

This pressure head is controlled by the pilot valve 53 and variesinversely relatively to the pressure head in the control pipe M. It willbe apparent that the valve 59 is biased in its closing direction by thepressure fluid in connection 62 which reacts on the diaphragm 56. Valve59 is biased to open by main reservoir pressure. The,

areas of the diaphragm 56 and the valve seat 63 are selected so that thedesired relation between control pipe pressure and pilot pressure in theconnection 43 is established.

The time during which charging of the volume 6| occurs is determinedbythe energization of the winding 34. If straight-air pipe pressure doesnot develop the master controller remains in application position andthe winding 34 remains energized. Under these conditions charging flowto volume 68 is uninterrupted and will after a definite time interval,dependent upon the pressure head in the connection 43 cause the switch12 to open and de-energize the winding 14 of the magnet valve 15. Thepipe 3| will be vented when the valve 15 is de-energized and will causean automatic brake application. The word automatic isused here toindicate that the brake application is initiated by the automatic brakeequipment.

If straight-air pipe pressure develops sufficiently to return the mastercontroller l5 to lap position the winding 34 will be de-energized andcharging of the volume 68 will be discontinued.

If there is a leak from the straight-air pipe, it will cause a pressuredifferential to develop between control pipe pressure and straight-airpipe pressure thus moving the master controller l5 to applicationposition. It will be apparent that the Winding 34 is again energized andcharging of the volume 63 will be resumed. The volume 68 is constantlyvented at a restricted rate, and since the charging flow, under theconditions described above is intermittent, the time required to chargethe volume 68, assuming a constant rate of charging flow, is determinedby the frequency of the cycling of the master controller.

For any given size of leak from the straight-air pipe the frequency ofthe cycling of controller |-5 will depend upon'the pressure head in thestraight-air pipe. Hence a minor leak might cause rapid recycling of themaster controller |5 when a heavy application is made. The high controlpipe pressure, however, will condition the pilot valve 53 so that arelatively low pressure head exists in the connection 43, therefore thecharging rate will be decreased. It will be seen that the frequency ofthe cycling determines the time intervals when charging flow to volume68 may occur and the pilot valve acts to control charging rate byvarying the pressure head.

By varying the pilot pressure inversely relatively to control pipepressure it is possible to compensate the safety device so that itsoperation is the same for a given size of leak from the straight airpipe regardless of the pressure in that pipe.

When the switch 12 has been opened and an automatic application of thebrakes initiated by de-energization of the winding 14, the brakes may bereleased only after the two-position selector has been shifted to changethe operation from the straight-air system to the automatic system.Thus, if the safety device applies the control pipe to vary the pressurehead at said 10 inlet inversely. relatively tocontrol pipe pressure;brake applying means independent. of said electrospneumatic brakesystem; and means respone sive to the development of pressure above apre-.-

determined value and serving in response there-1 15 toto. operate saidbrake applying means.

2. The combination defined in claim 1 in which said pressure controlledvalve: includes. a. valve member in said inlet; said valvev member beingbiased in its. openingdirection by pressure in said source; and fluidpressure motor means. actuated by pressure in said control pipe andserving when actuated to bias said valve member in a closing direction.

JOHN VAN VARICK ELSWORTH.

Beierenees- Cited in the file of this patent STATES PATENTS Number NameDate 1 ,136,051 Turner Apr. 20, 1915 2,527,920 Elsworth Oct. 31, 1,950

